The production was divided in to several model years by the manufacturer. Which model year a car belongs to is decided by the vehicle identification number (VIN) and not the date of first registration. The breaking points (a specific VIN) for each model year are listed below. All VIN series assigned to the M3 E46 were not used completely. There are skipped VINs between certain model-years and this also occurs within a couple of MYs. The change to a new model year usually takes place in the end of August or early September.
The VIN is found below the windscreen and to the right of the
engine compartment and certain markets also have a sign with the VIN at the bottom part of the windscreen.